Endoscopy is a term we often hear in the field of medicine. It is that device that doctors use to probe inside our bodies, to peer into the interiors. But now, the principle of endoscopy has been employed in an entirely different area — pyramids.

Last month, scientists inserted endoscopes into a ‘void’ above the entrance of the Great Pyramid outside Cairo. A previously unknown empty corridor with a gabled roof was found, but apparently it leads to nowhere. If they had hopes of finding a cache of gold artefacts — as they did in the boy king Tutankhamun’s tomb a hundred years ago — they would have been disappointed. But they are excited regardless, because the endoscope has let them take a peek into this mysterious empty corridor whose purpose and whereabouts were so far lost in the recesses of history.

It was another field of science that put them wise to the existence of the void inside the man-made mountain of rock. The ‘muon detectors’ that scientists have built have been used for the same purpose. Muons are sub-atomic particles that form when cosmic rays interact with the earth’s atmosphere. They are present everywhere. In fact, all of us get a shower of muons everyday. The unique fact about these muons is that when they travel through dense medium — like a big man-made mountain of rock — they slow down and die. When instruments catch more muons emerging on the other side, scientists know that at least a part of their travel path was through empty space — or a void.